The present invention relates in general to sports racquets, such as tennis rackets, badminton racquets, squash racquets and racquetball racquets used for hitting a projectile such as a ball, and more particularly to a method of stringing a sports racquet used for hitting a projectile.
In the most conventional sort of strung sports racquets, the striking area is defined by a head frame that is roughly oval in shape. xe2x80x9cRacquet,xe2x80x9d as used herein, encompasses racquetball racquets, tennis rackets, badminton racquets, squash racquets and any other sports implement that has a head which is strung with string or netting and which is designed to intercept and return a projectile. Holes are made through the frame, typically in the plane of the strung area, for the passage of string therethrough. Racquets are generally strung such that one string weaves through the holes that are positioned on opposite sides of the frame in a consecutive fashion, forming multiple string segments. As a result, two directly connected segments of the string are situated adjacent each other in the strung racquet.
As the ball impacts a string, a tensile force is placed on the string which will have a tendency to pull the string through the string hole, and this tensile force is communicated to the adjacent string segment of the string. If the adjacent string segment is not also impacted, there would be a tendency of the adjacent strung segment to relieve some of the tensile force by lengthening. However, when two adjacent string segments are impacted at the same time, there is no opportunity for one string segment to relieve the stress placed on the other. Instead, tensile force is exerted on both string segments toward the projectile but in opposite directions on the string of which the string segments are a part, tending to pull the string apart. This acute stress shortens the life of the string and causes string failure. Further, where a large component of a ball""s momentum is absorbed by a single string segment, other segments adjacent on the continuous string to the impacted segment can contribute to the impacted strings elongation and resiliency, thereby contributing a more lively feeling to play. But where two or more segments that are adjacent each other on the continuous string absorb substantial portions of a ball""s impact, they are less available in permitting each other to yield or deflect. This results in a more wooden or board-like feel to play.
Thus, it is desirable to improve the life of strings of a sports racquet and to reduce the amount of stress the ball exerts at impact on each of the connected string segments, and it is desirable to enhance liveliness and resiliency in the behavior of impacted string segments.
One aspect of the invention is a method used to string a sports racquet for hitting a projectile and the string racquet produced thereby. The method includes the step of drawing a string from a first side of a racquet frame toward a second side opposite the first side to form a first string segment. The string is strung through a string anchoring point at a first location on the second side and drawn from the first location on the second side to a second location on the second side. The string is then strung through a string anchoring point at the second location and passed back to the first side of the frame. The second side is spaced from the first side a predetermined distance that is preselected such that the projectile cannot substantially impact both the first and second string segments when the racquet hits the projectile.
Another method for stringing a sports racquet includes the step of drawing a string from a first side of the racquet frame toward a second side opposite the first side to form a first string segment. The string is strung through a first string hole at a first location on the second side. The string is drawn from the first location on the second side to a second location on the second side spaced from the first location. The string is then strung through a second string hole at the second location. The string is then passed back to the first side of the frame with at least two other string holes on the frame interposed between the first and second string holes. The result is a string racquet in which string segments that are adjacent each other on the string occupy positions in the string that are substantially parallel to each other but which are spaced apart by at least two other, and in some embodiments three or more, string segments.
Another aspect of the invention is directed to a string anchoring system for a sports racquet. The string anchoring system preferably includes a bumper having an outer surface, an inner surface and a plurality of anchoring points formed therethrough. The bumper surrounds an outer edge of a frame of the sports racquet and the anchoring points are adapted to guide a string through the frame of the sports racquet. A first string path is formed in the outer surface of the bumper between a first and second location and a second string path is formed in the outer surface of the bumper between a third and fourth location. The third, first, fourth and second locations are linearly arranged along the outer surface such that the fourth location is between the first and second locations. The second string path is displaced from the first string path such that the first and second string paths are adapted to receive string portions wherein the string portions disposed in the string paths do not saw at each other. In a preferred embodiment, the string anchoring system defines three such overlapping string paths, which however are routed so as to substantially avoid each other. Alternatively, the string paths may be formed by an external top surface of the racquet frame itself rather than in a bumper.
The present invention is applicable to shafted as well as nonshafted racquets and to racquets of conventional string designs as well as xe2x80x9clongstringxe2x80x9d designs (see, e.g., U.S. Pat. No. 5,919,104 assigned to the assignee hereof). The present invention enhances string life as well as resiliency in play in that a ball cannot impart as much energy into two string-adjacent string segments at the same time. Therefore, these string-adjacent string segments (i.e., having the relation to each other shown in FIG. 2) are more able to contribute to the resiliency and deflection of those string segments taking most of the force.